It is known in the art that imaging display materials are utilized for advertising as well as decorative displays of images. Since these display materials are used in advertising, the image quality of the display material is critical in expressing the quality message of the product or service being advertised. Further, a display image needs to be high impact, as it attempts to draw consumer attention to the display material and the desired message being conveyed. Typical applications for display material include product and service advertising in public places such as airports, buses and sports stadiums, movie posters, and fine art photography. The desired attributes of a quality, high impact display material are a slight blue density minimum, durability, sharpness, and flatness. Cost is also important, as photographic display materials tend to be expensive as the imaging process is equipment intensive and requires processing chemicals. For imaging display materials, traditional paper bases are undesirable as they suffer from a lack of durability for the handling and captured display of large format images. The use of display materials such as lithographic prints or ink jet prints could be expanded if image quality was improved.
In the formation of color paper it is known that the base paper has applied thereto a layer of polymer, typically polyethylene. This layer serves to provide waterproofing to the paper, as well as providing a smooth surface on which the photosensitive layers are formed. The formation of a suitably smooth surface is difficult requiring great care and expense to ensure proper laydown and cooling of the polyethylene layers. The formation of a suitably smooth surface would also improve image quality as the display material would have more apparent blackness as the reflective properties of the improved base are more specular than the prior materials. As the whites are whiter and the blacks are blacker, there is more range in between and, therefore, contrast is enhanced. It would be desirable if a more reliable and improved surface could be formed at less expense.
Prior art photographic reflective papers comprise a melt extruded polyethylene layer which also serves as a carrier layer for optical brightener and other whitener materials, as well as tint materials. It would be desirable if the optical brightener, whitener materials, and tints, rather than being dispersed throughout the single layer of polyethylene, could be concentrated nearer the surface of the layer where they would be more effective optically.
Prior art photographic reflective display materials have light sensitive silver halide emulsions coated directly onto a gelatin coated opacified polyester base sheet. Since the emulsion does not contain any materials to opacify the imaging element, white pigments such as BaSO.sub.4 have been added to the polyester base sheet to provide an imaging element with both opacity and the desired reflection properties. Also, an optical brightener is added to the polyester base sheet to give the sheet a blue tint in the presence of an ultraviolet light source. The addition of the white pigments into the polyester sheet causes several manufacturing problems which can either reduce manufacturing efficiency or reduce image quality. The addition of white pigment to the polyester base causes manufacturing problems such as die lines and pigment agglomeration which reduce the efficiency at which photographic display material can be manufactured. It would be desirable if the optical brightener, whitener materials, and tints, rather than being dispersed throughout the polyester base sheet, could be concentrated nearer the surface where they would be more effective optically and improve manufacturing efficiency.
Prior art reflective photographic materials with a polyester base use a TiO.sub.2 pigmented polyester base onto which light sensitive silver halide emulsions are coated. It has been proposed in WO 94/04961 to use an opaque polyester containing 10% to 25% TiO.sub.2 for a photographic support. The TiO.sub.2 in the polyester gives the reflective display materials an undesirable opalescence appearance. The TiO.sub.2 pigmented polyester also is expensive because the TiO.sub.2 must be dispersed into the entire thickness, typically from 100 to 180 .mu.m. The TiO.sub.2 also gives the polyester support a slight yellow tint which is undesirable for a photographic display material. For use as a photographic display material, the polyester support containing TiO.sub.2 must be tinted blue to offset the yellow tint of the polyester causing a loss in desirable whiteness and adding cost to the display material. It would be desirable if a reflective display support did not contain any TiO.sub.2 in the base and could be concentrated near the light sensitive emulsion.
Prior art photographic display materials, while providing excellent image quality, tend to be expensive when compared with other quality imaging technologies such as ink jet imaging, thermal dye transfer imaging, and gravure printing. Since photographic display materials require an additional imaging processing step compared to alternate quality imaging systems, the cost of a reflective photographic display can be higher than other quality imaging systems. The processing equipment investment required to process photographic reflective display materials also requires consumers to typically interface with a commercial processing lab increasing time to image. It would be desirable if a high quality reflective display support could utilize nonphotographic quality imaging technologies.
Photographic reflective display materials have considerable consumer appeal as they allow images to be printed on high quality support for home or small business use. Consumer use of photographic display materials generally have been cost prohibitive since consumers typically do not have the required volume to justify the use of such materials. It would be desirable if a high quality reflective display material could be used in the home without a significant investment in equipment to print the image.
Prior art photographic display material uses polyester as a base for the support. Typically the polyester support is from 150 to 250 .mu.m thick to provide the required stiffness. A thinner base material would be lower in cost and allow for roll handling efficiency, as the rolls would weigh less and be smaller in diameter. It would be desirable to use a base material that had the required stiffness but was thinner to reduce cost and improve roll handling efficiency.